Most data communications networks today rely heavily on shared medium, packet-based LAN technologies for both access and backbone connections. These networks use bridges and routers to connect multiple LANs into global internets. An internet router must be capable of processing packets based on many different protocols, such as IP, IPX, DECNET, AppleTALK, OSI, SNA and others. The complexities of building networks capable of routing packets on the global internet using different protocols is a challenge for both vendors and users.
In U.S. Ser. No. 08/188,238 to Dobbins (see related applications above), there is described a new secure fast packet switching (SFPS) technology which provides the same or better reliability and security as routers, but with much greater performance and without an increase in cost. The SFPS system avoids the complexities and costs of providing multi-protocol routers. Also, the SFPS system provides capabilities which routers do not, such as the ability to create separate logical work group LANs on the same physical network and the ability to guarantee a quality of service (QOS) by providing dedicated switched paths through the network.
SFPS provides high performance packet switching based on physical layer addresses such as source and destination MAC IDs--the unique medium access control (MAC) address assigned to each end system by the IEEE. End-to-end connections are determined by a network management application that provides security and best path routing determinations based on a number of constraints. By switching packets based only on MAC layer information, network infrastructure remains protocol insensitive.
More specifically, SFPS uses source and destination MAC addresses which alone, or in combination with an input port on a switch, form a unique "connection identifier" for any communication exchange between designated end systems. As an example:
together form a "tuple" bound to a specific unidirectional flow from a source address to a destination address. All packets that have this tuple are automatically switched according to the operation of the SFPS.
Network infrastructures are built around a core switching fabric, which provides the physical paths or routes that allow users to send information to one another. Access to the switching fabric is gained through an access port. Access ports provide several functions--most importantly, they provide security and accounting services. End systems such as personal computers (PCs), workstations and servers connect to an access port using one or more access technologies such as Ethernet, Token Ring, FDDI, or ATM.
In traditional bridge and router devices, each packet is treated as an independent unit of data which is individually processed by application of access and security constraints, as well as path determination. In contrast, with SFPS this processing is done only on initial probe packets which are decoded, and through use of a central directory of end system constraints policy, call attributes, location, paths, quality of service, etc., the connection is either rejected or accepted. If accepted, the path is determined and switches along the path are "programmed" to allow subsequent packets on this "connection" to be switched. In either case, subsequent datagrams are either switched or discarded without having to reapply all of the security and access control and path determination logic.
The SFPS switching technology may be constructed as: software objects which exist in embedded devices as firmware; software objects which are part of an application on a commercial computer system; application specific integrated circuits (ASIC); or functionally equivalent hardware components.
It is common for internetworking devices to "route" the protocols that a device supports, and "bridge" the protocols that are not supported for routing. In addition, some protocol frames (such as DECs LAT) are actually unroutable. In SFPS switches, there are protocol-specific call processors to route protocol-specific broadcast frames (note that unicast frames can be processed by a "generic" call processor that does not decode or translate the frame at all, but instead makes the connection request based on the source and destination unicast MAC addresses in the frame). However, a problem arises in that an SFPS switch has nothing equivalent to bridging of multicast and broadcast packets for non-supported protocols. Thus, until a protocol-specific call processor is implemented in a switch, the switch must discard any broadcast or multicast frames it does not understand.